JP4620558B2 - Silicone rubber molding method - Google Patents

Description

The present invention relates to a method of molding a silicone rubber, in particular, to a method of molding a silicone rubber.

Molding method of the silicone resin, a room temperature curable silicone rubber (room temperature vulcanization (RTV) silicon rubber) flowed to the bottom layer of the mold recesses of the mold, followed by the uncured silicone rubber sheet (silicon rubber sheet) mold It puts into the top layer of a recessed part, and finally heat-compresses both, it sulphides and shape | molds (refer patent document 1).

When performing thermal compression, the RTV silicone rubber is still a liquid, so after performing the thermal compression, a bleeding phenomenon occurs and the molded pattern is often blurred. This situation is even more pronounced, especially when producing very small patterns. Therefore, such a method is preferably applied to the production of a large pattern, but the rate of defective products is still relatively high.

JP 2000-317966 A

The main object of the present invention is to provide a method for molding silicone rubber in which no bleeding phenomenon occurs.
Another object of the present invention is to provide a method for molding a silicone rubber which can produce a multilayer pattern as required.

In order to achieve the above object, a method for molding a silicone rubber according to the present invention includes the following steps.
(1) A mold having a mold recess inside is prepared. The mold recess is formed from at least one pattern layer and a base layer located above the one pattern layer.

(2) passing a liquid at room temperature curable silicone rubber (room temperature vulcanization (RTV) silicon rubber) and the pattern layer of the mold.
(3) The room temperature curable silicone rubber is heated to advance the initial sulfidation molding.
(4) A surface treatment agent is applied to the surface of the room temperature curable silicone rubber.

(5) high-temperature-curable silicone rubber (high temperature vulcanization (HTV) silicon rubber) are placed in the basal layer of the mold.
(6) Heat compressing room temperature curable silicone rubber and high temperature curable silicone rubber.
(7) When the mold is opened, a silicone rubber product is completed.

The structure and features of the present invention will be described with reference to the drawings of the following embodiments.
(A) A mold 10 is prepared.
As shown in FIG. 1, the mold 10 has a lower mold 12 and an upper mold 14, the lower mold 12 has a multilayer mold recess 16, and the mold recess 16 is in order from top to bottom. Thus, the first pattern layer 18, the second pattern layer 20, and the base layer 22 are provided.

(B) flowing a liquid at room temperature curable silicone rubber 24 into the first pattern layer 18 of the mold 10 (room temperature vulcanization (RTV) silicon rubber).
As shown in FIG. 2, in this step, a predetermined amount of RTV silicone rubber 24 is flowed through the first pattern layer 18 of the mold 10 by micro injection and automated control. The RTV silicone rubber 24 can exhibit different colors and is injected into a predetermined area of the first pattern layer 18 of the mold 10 by design.

(C) The RTV silicone rubber 24 is heated to advance the initial sulfidation molding .
The lower mold 12 is transferred to an oven (not shown in the figure) and heated, and the RTV silicone rubber 24 is set by setting the heating temperature between 120 ° C. and 180 ° C. and the time between 15 seconds and 25 seconds. Is formed by sulfidation .

(D) The RTV silicone rubber 24 is cooled.
After the heating operation is completed, the lower mold 12 is moved to a cooling device (not shown in the figure), and a cooling liquid (ordinary water) having a cooling device temperature between 5 ° C. and 20 ° C. is circulated and flowed. The RTV silicone rubber 24 is cooled to room temperature.

(E) The RTV silicone rubber 24 adhering to places other than the first pattern layer 18 is removed.
In the process of microinjection, a portion of the RTV silicone rubber 24 (not shown in the drawing) may not be dropped on the first pattern layer 18 but may be dropped on the lower mold 12. Therefore, it is necessary to wipe off this portion of the RTV silicone rubber 24 (not shown in the figure) with a cloth.

(F) As shown in FIG. 3, a surface treatment agent (primer) 26 is applied to the surface of the RTV silicone rubber 24. As the surface treatment agent 26, for example, a known adhesion primer is used.
The surface of the RTV silicone rubber 24 after sulfidation molding has a glossy and smooth state, and is therefore difficult to bond with another silicone rubber. In order to activate the surface of the RTV silicone rubber 24 and bond the RTV silicone rubber 24 to another silicone rubber, it is necessary to apply a surface treatment agent 26 to the surface of the RTV silicone rubber 24.

  (G) As shown in FIG. 4, the liquid RTV silicone rubber 28 is allowed to flow through the second pattern layer 20 of the mold 10, and then steps such as heating, cooling, cleaning, and application of the surface treatment agent 30 are sequentially performed. To proceed.

(H) As shown in FIG. 5, placed basal layer 22 of high-temperature-curable close to the size and shape silicone rubber 32 of the die 10 (high temperature vulcanization (HTV) silicon rubber) to the base layer 22.

(I) As shown in FIG. 6, the upper mold 14 is put on, and then the mold 10 is transferred to the cavity chamber 34 to perform thermal compression.
In order to prevent air from remaining in the mold recess 16 or the silicone rubber of the mold 10, the air is first removed from the cavity chamber 34, and pressure is applied to the mold 10 by the compression head 36 in the process. After applying pressure repeatedly, air is sent into the cavity chamber 34, and the heating time is set between 30 seconds and 450 seconds, and heating is performed between 180 ° C. and 250 ° C. Subsequently, by repeating the above steps twice or twice to eight times, the air in the mold recess 16 or the silicone rubber is completely removed, and these silicone rubbers are integrated.

(J) When the mold 10 is opened, the silicone rubber product 38 is completed.
As shown in FIG. 7, the silicone rubber product 38 has a base 40 formed from the HTV silicone rubber 32 and a pattern 42 formed from the RTV silicone rubber 24 and positioned on the base 40. Since all the RTV silicone rubbers 24 are changed to solid before reaching the thermal compression step (step (i)), the bleeding phenomenon does not occur when the thermal compression process is performed. Therefore, the method according to the embodiment of the present invention can produce a very small pattern. When the present inventor actually operated, English letters with a minimum size of 0.2 mm can be formed . And the defective rate of the silicone rubber product 38 produced by the method according to the embodiment of the present invention is extremely low.

  Silicone rubber products 38 made by known methods have only a single layer pattern, whereas silicone rubber products 38 made by methods according to embodiments of the present invention have multiple layers and three-dimensional patterns. As shown in FIG. 7, the pattern 42 is formed by depositing a bottom layer pattern 44 and a top layer pattern 46 on the bottom layer pattern 44. The bottom layer pattern 44 is formed from the RTV silicone rubber 24 in the first pattern layer 18 of the mold 10, and the top layer pattern 46 is formed from the RTV silicone rubber 28 in the second pattern layer 20 of the mold 10. In the method according to the embodiment of the present invention, a three-dimensional pattern of three layers or three or more layers can be produced by designing the mold 10 to have three or three or more pattern layers.

  In addition, the method according to the embodiment of the present invention can produce a silicone rubber product having a multi-dimensional pattern on both sides. As shown in FIG. 8, the lower mold 12 of the mold 10 has a slight pattern layer 18, a pattern layer 20, and one base layer 22, and the upper mold 14 has a slight pattern layer 48 and a pattern layer 50. Therefore, it is possible to produce a silicone rubber product having a pattern on both sides by performing the above-described steps in the same manner.

  Also, if it is necessary to thicken the base of the silicone rubber product or make a pattern on the back of the base layer depending on the situation, it has an upper mold with a base layer (not shown in the figure) or simultaneously with a pattern layer and a base layer Using the upper mold (not shown in the figure), the desired silicone rubber product can be obtained by putting HTV silicone rubber or RTV silicone rubber into the upper mold according to the above-described steps.

It is a schematic diagram which shows the lower metal mold | die of the shaping | molding method of the silicone rubber by one Example of this invention. It is a schematic diagram which shows the state which flows the RTV silicone rubber of the shaping | molding method of the silicone rubber by one Example of this invention to a 1st pattern layer. It is a schematic diagram which shows the state which apply | coats a surface treating agent to the surface of RTV silicone rubber of the shaping | molding method of silicone rubber by one Example of this invention. It is a schematic diagram which shows the state which flows the RTV silicone rubber of the shaping | molding method of the silicone rubber by one Example of this invention to a 2nd pattern layer, and applies a surface treating agent on the surface. It is a schematic diagram which shows the state which flows the HTV silicone rubber of the molding method of the silicone rubber by one Example of this invention to a base layer. It is a schematic diagram which shows the state which places the metal mold | die of the molding method of the silicone rubber by one Example of this invention in a cavity chamber, and performs heat compression. It is a perspective view which shows the metal mold | die which produces the silicone rubber product of the double-sided pattern of the molding method of the silicone rubber by another Example of this invention. It is a schematic diagram which shows the state which produces the silicone rubber product of the double-sided pattern of the shaping | molding method of the silicone rubber by another Example of this invention.

Explanation of symbols

  10 mold, 12 lower mold, 14 upper mold, 16 mold recess, 18 first pattern layer, 20 second pattern layer, 22 base layer, 24 RTV silicone rubber, 26 surface treatment agent, 28 RTV silicone rubber, 30 Surface treatment agent, 32 HTV silicone rubber, 34 cavity chamber, 36 compression head, 38 silicone rubber product, 40 base, 42 pattern, 44 bottom layer pattern, 46 top layer pattern, 48 pattern layer, 50 pattern layer

Claims (11)

Preparing a mold having a mold recess therein, wherein the mold recess is formed of at least one pattern layer and a base layer located above the one pattern layer; and
Room temperature curable liquid silicone rubber of (room temperature vulcanization (RTV) silicon rubber) and step 2 to flow into the pattern layer of the mold,
Step 3 of heating the room temperature curable silicone rubber to advance the initial sulfidation molding,
Applying a surface treatment agent (primer) to the surface of the room temperature curable silicone rubber; and
High temperature curing type silicone rubber (high temperature vulcanization (HTV) silicon rubber) to Step 5 Add the basal layer of the mold,
Step 6 of thermally compressing the room temperature curable silicone rubber and the high temperature curable silicone rubber;
When the mold is opened, the step 7 is completed for the silicone rubber product,
A method for molding silicone rubber comprising:
Step 6 further includes
Placing a mold in the cavity, step a;
Removing air from the cavity and repeatedly applying pressure to the mold b;
Step c for introducing air into the cavity;
Step d for heating the mold;
A method for forming a silicone rubber, comprising:   2. The method of molding silicone rubber according to claim 1, wherein in step 3, the heating temperature is between 120 ° C. and 180 ° C., and the time is between 15 seconds and 25 seconds. The method for molding a silicone rubber according to claim 1, further comprising the step of cooling the room temperature curable silicone rubber to room temperature after step 3 is completed.   The cooling step is to transfer the mold to a cooling device, and the cooling device has a circulating flow of cooling water having a temperature of 5 ° C to 20 ° C. Molding method. The method for molding a silicone rubber according to claim 1, further comprising a step of removing the room temperature- curing silicone rubber dripped to a place other than the pattern layer after Step 3 is completed.   2. The method for molding silicone rubber according to claim 1, wherein steps a to c are repeated before reaching step d.   The method for molding a silicone rubber according to claim 1, wherein the heating temperature is between 180 ° C and 250 ° C, and the heating time is between 30 seconds and 450 seconds. A mold composed of a lower mold and an upper mold is prepared, the lower mold has a mold recess, and the mold recess has a few pattern layers and one base layer located above these pattern layers. Step 1 formed from
Room temperature curable liquid silicone rubber of (room temperature vulcanization (RTV) silicon rubber) and step 2 to flow into the pattern layer of the mold,
Step 3 of heating the room temperature curable silicone rubber to advance the initial sulfidation molding,
Applying a surface treatment agent (primer) to the surface of the room temperature curable silicone rubber; and
Step 5 repeating Step 2 to Step 4 until all pattern layers are filled with room temperature curable silicone rubber;
High temperature curing type silicone rubber (high temperature vulcanization (HTV) silicon rubber) to Step 6 Add the basal layer of the mold,
Step 7 of thermally compressing the room temperature curable silicone rubber and the high temperature curable silicone rubber;
Opening the mold, step 8 completes the silicone rubber product,
A method for molding silicone rubber comprising:
Step 7 further includes
Placing a mold in the cavity, step a;
Removing air from the cavity and repeatedly applying pressure to the mold b;
Step c for introducing air into the cavity;
Step d for heating the mold;
A method for forming a silicone rubber, comprising: 9. The silicone rubber according to claim 8, wherein the upper mold of the mold has at least one pattern layer, and room temperature curable silicone rubber is put into the pattern layer by the method of Step 2 to Step 5. Molding method. The upper mold of the mold has a base layer, a high temperature curable silicone rubber is put therein, a surface treatment agent is applied thereon, and then the heat compression step of Step 7 is advanced. Item 9. A method for molding silicone rubber according to Item 8. The upper mold of the mold has at least one pattern layer and one base layer, and room temperature curable silicone rubber is placed in the pattern layer by the method of Step 2 to Step 6, and the base layer has a high temperature. 9. The method of molding a silicone rubber according to claim 8, wherein a curable silicone rubber is placed, a surface treatment agent is applied on the high temperature curable silicone rubber, and then the thermal compression step of Step 7 is advanced.

Images